One big problem with this is that when it opens CCleaner and does its cleaning the windo to close Google Chrome keeps popping up. So to properly clean Chrome you have to close it.
Which kind of defeats the purpose of this extension right?

Not working here, seems to be a win7 problem.. But i'm a little concerned too, it runs an .exe file .. Is that really supposed to be possible, that means extensions can contain virus ?

Yes. Even without exe running capability, you could implement a virus in an NPAPI plugin. That's why there's a warning when you install extensions. (There is no warning for themes, because themes cannot run JS or include NPAPI plugins.)